Twin study gives unexpected information on genetics of diabetesReversing one of the beliefs concerning diabetes, a British researcher maintains that the juvenile-onset, insulin-dependent type of the disease may not be primarily genetic in origin, whereas the adult form has a stronger genetic component than previously thought.David H. Pyke, MB, head of the Diabetes Program at Kings College Hospital, London, made the surprising assertion after following 150 pairs of identical twins that were either concordant or discordant for diabetes mellitus. The age of 45 years was used to separate juvenile-onset from maturity-onset diabetes.There were 106 pairs of twins whose disease appeared before age 45; these pairs were about equally divided between concordant and discordant. In 54 of the 106 pairs, the disease had developed in both twins before age 45, while in 52 pairs, only one twin was diabetic. Thus, Dr Pyke concluded that factors other than